Inert-gas shielded continuous-feed metal-arc welding apparatus



June 6, 1950 A w BAIRD 2,510,205

INERT GAS SHIELDEDCONTINUOUS FEED METAL ARC WELDING APPARATUS Filed Feb. 11, 1949 2 Sheets-Sheet 1 INVENTOR ALBERT W.BAIRD ATTORN EY June 6, 1950 A. w. BAlRD 2,510,205

INERT GAS SHIELDED CONTINUOUS FEED METAL ARC WELDING APPARATUS Filed Feb. 11,- 1949 2 sheets-sheet 2 *E YMOTOR @97 151 EEA JZ CONTROL ,/TRANSFORMER 155 155" To WORK PIECE WELDlNG CURRENT CrN'E/Rv M [SUPPLY :40 15 52 To Bus BAR ,/wELDINC ROD 34 5,0/6

5g 36,/ CAs L MOTOR Ef/ 5 OER/Ess y l fig- /.57 DSwofw EL//Wm f 16g 15g v L Y 165 195 gfgl' 6E L 165) CONTACTOR* cENEoRxToR-fj: 15j 137\ 167` 14 TRANsFORMER 157 ggg L MOTOR f t V v 5 COSvPEERErEOR f CONTROD k21'0 Us D@` 197i l L 155 541/ 'Roo 10 wELDlNC CURRENT CABLES 1 AW )4 B55 lNvENToR 543 wORK ALBERT W. BAIRD @95? y mw ATTORNEY Patented `lune 6, 1950 INERT-GAS SHELEDED CONTINUOUS-FEED METAL-ARC WELDING VAPPARATUS Aibert--W.-Baird, Cranford, N. LJ., assigner to The Linde Air Products Company, a 4cor-poration of Ohio Application February 11, 1949, Serial No. 75,738

(Cl. Z19-S) 4 Claims.

This invention relates to electric arc welding with ller metal composed of a bare Wire through which welding current is conducted and which is continuously fed to the welding Vzone while such Welding zone is shielded by a gas stream consisting essentially of inert gas such as argon and/or helium;

This application is a continuation-in-part of my application, Serial No. n44,303, led August 14, 1948, for yFlexble'submerged melt welding machine. The head of vsuch machine is not entirely suitable Vfor overhead or vertical welding, due to the force of gravity on the granular fflux. Also the use of such granular flux renders the process unsuitable for Welding certain metals. For example, submerged melt welding is not suitable for AWelding light metals composed principally of Kaluminum and/or magnesium. There is also 4the problem of removing unmelted granular flux and cleaning the fused and hardened flu-X from the weld. Aluminum, magnesium and other light metals having a relatively low melting point compared With that of steel, when fed as 'wire through a guide and electrical contactnozzle which controls the direction of the path of the Wire and transfers Welding current to the moving wire, also tend to soften and sometimes melt Awithin the nozzle, due to internal arcing, and heating of the nozzle because of the nozzles proximity to the Welding `zone. Melting and welding of the filler metal in the nozzle also occurs AWhen ythe wire feed is too slow, or stopped while the welding current is on and contact by the wire With the welding zoneis not broken. In such case the `nozzle requires considerable time and eifort to repair.I inasmuch vas theV nozzle, with the wire frozen or Welded inside, must be removed from lthe apparatus and replaced with a lnew nozzle. Another problem results from contamination of the weld due to air and/or moisture entrained with the moving wire as it is fed toward the Welding zone.

Therefore, the main object of the present invention is to provide a flexible Welder vwhich is suitable for overhead and vertical as Well as horizontal Welding Without granular flux, which can also be used for welding any metal including relatively light and lowl melting point metals such as magnesium and aluminum, as well as for welding stainless-steel, carbonsteel and other metals.

Another object'is to provide an improved gas shielded continuous-feed metal-arc Welding process. A further object is to provide a novel welding gun which is simple and economical in its parts, light in weight, easy tomanipulate, and which enciently conducts Welding current to a moving metal wire electrode and, at the same time, effectively transmits and modifies the flow of inert gas so that it properly shields the electrode and Welding zone from the atmosphere as well'as from air which'otherwise would be en- Welding operation. An important object of the invent-ion is to provide improved nozzle means which serves efficient-ly to conduct welding current tofthe wire-as it is'fed, and smoothly to guide the wire as directed, which vmeans is provided with eiicient'cooling meansfor keeping the metal of the wire relatively cool andytherefore, stiiso that ythe wire can 'be continuously pushed through the nozzle without danger of stoppage due to overheating and Welding of the Wire in such nozzle means. A further vobject is to provide-automatic circuit means, under the control of thewoperator, Ywhich insures operation of the wire feed motor so long as Athe welding current circuit is-closed. V'These and other objects will be apparent to those skilled in the lart from` the following description.

Accordi-ng to the invention there'is provided a flexible Welder for electric welding of the type in which a bare relatively small Wire of weld metal, such as stainless steel -or'aluminum isfed vrelatively rapidly-toward Work'composed of the .1 metal beingvwelded Whilewvelding current ows through such Wireandthe Work, and the welding zone yandl the adjacent Wire are shielded from the atmosphere with a gas stream composed principally of-inert-gas such'las argon and/or helium during the Welding operation. lSuch Welder comprisesV a carriage on-Which-meansfor supplying the inert gas (a cylinder containing compressed gas) and means forvsuppl-ying the welding wire (a Wire reel vand Va wire feed motor) are-both mounted. Afflexible hose hasA one endHat-tached tothe carriage, the free end of theA hose-being connected to a novel welding gun having coaxial nozzles-throughwhich the welding Wire andrvgas are discharged. The hosecontainslexible means for conducting gas from the carriage tothe head, flexible means for transmitting .the wire, and exible welding current. and control conductors. Withinthe gun ismounted .a novel-head which serves as a terminal for all of such supply means, asa brushfor conducting welding current to the Wireasit passes therethrough, as adistributor within the. gunfor the inert gas, as anair and moisture dam, ,and as a Ysupportfor holdinga Welding wire contact nozzlein proper position centrally within a gas nozzle or cup. .The Wire contact nozzle is cooled somewhat: by the gas in a gas expansion vchamber and assures good con duction of Welding current to the wire-especially in the curved-type form of nozzle. The head also is provided with unique means for supplying inert gas to the Wire passage, so that the flow of air and/or moisture through such passage along with the moving wire is minimized by back-flow of the gas-assuring non-contamination of the Weld by such air and/.or moisture. As a result the gun is compact, eiiicient and cool in operation, and due to the flexible hose can be used for manual welding without diiiiculty in otherwise hard-to-get-at places; and the entire machine can be readily moved about, carrying with it the needed supplies of gas and wire for continuous use ior a substantial amount of welding.

Further, according to the invention, there is provided a novel combined electric brush and gas distribution block or head in a welding gun, which guides the Welding wire through the gun and changes the direction of the gas flow in such a way that the gas flows without turbulence annularly out of the gas nozzle around the welding wire as the latter emerges from its nozzle on the way to the welding zone. An automatically operated relay is provided for controlling the wire feed motor, the motor being turned on and off automatically in response to the flow of Welding current, so that feeding movement of the wire through the nozzle continues as long as the welding current circuit is closed.

The welding current may be alternating or direct-reverse or positive polarity, the Welding current density and wire feed being closely correlated so that melting of the Wire before it reaches the welding zone is avoided.

In the drawing:

Fig. 1 is a view in elevation of a gas shielded continuous feed metal-arc Welding machine illustrating the invention;

Fig. 2 is a fragmentary view of the hose, a part of the gun being broken away to show the wire nozzle;

Fig. 3 is an enlarged view in cross-section of a modication of the gun;

Fig. 4 is a view similar to Fig. 3 of another modification of the gun;

Figs. 5 and 6 are fragmentary sectional views taken on lines 5-5 and 6 6 of Fig. 4;

Fig. 7 is a ilow diagram; and

Fig. 8 is a circuit diagram of the invention.

As shown in Fig. 1, a machine A comprises a wheeled dolly lli on which are mounted a Wire reel I2 containing a control box i4, and a compressed argon or helium gas cylinder I6 having a valve I6 to which is connected a gas line provided With a gas pressure regulator 20, a flowmeter 2`2 and a pipe 24. Electric cables 26 and 26 leading to the dolly i6 are adapted to be connected to suitable sources of control circuit current, and welding current, respectively. The dolly IU contains a wire or rod feed motor M and suitable means including an idler roll 36 and a motor driven roll 32 for positively feeding a rod or wire 34 of filler metal from the reel l2, through a ilexble tube 36. Another flexible hose 38 is connected, through a solenoid valve 39 within the dolly Il), to the gas pipe 24; and flexible welding current conductors 40 are connected to the welding current cable 28 by suitable circuit means in the dolly. Such tubes and conductors extend into a flexible hose 42 through a bushing 54 which couples one end of such hose to a suitable bracket in the dolly I0.

A welding gun 46 is coupled to the free end of the hose 52 by suitable means including a metal head or block 48 which serves as a terminal for tubes 35 and 38 and conductors 56, as well as a bus-bar or brush for conducting welding current to the wire 36, as a port for discharging into the gun gas delivered by the tube 38, and as a support for a, wire contact nozzle 56 composed mainly of copper. The Wire nozzle 50 is located centrally within a gas cup or nozzle 52, so that gas delivered to the interior of the gun flows outwardly therefrom in an annular stream around the wire nozzle 56-shielding the end of the wire 34 from the atmosphere as it emerges from the nozzle 5i), the gas flowing over and also shielding from the atmosphere the welding zone on the work W. The gun i6 is substantially gas-tight, except for the gas inlet and outlet thereof, and is provided opposite the nozzle 52 with a removable transparent cover or window 53 which is composed of a sheet of mica or other suitable material. The work W is grounded by a conductor 54, so that the welding current iiows through the metal wire 35 and the work W during the welding operation. Operation of the machine A is controlled by a handy switch box 56 containing a motor reversing switch 58, an inching switch 66 and an indieating lamp 62, which are connected to elements inside, or mounted on the dolly I6 by means of insulated wires in a flexible cable 64.

In considering the operation of the machine A, Figs. 1 and 2, the Wire 34 is positioned in the gun 4&6 for welding by pressing and releasing the jog button 6,0 on the remote control box 56 which is electrically connected to the control means lli in the reel I2 by suitable insulated conductors in the cable 6d, the inert gas flow is then started, the welding current supply circuit is connected (upon closure of the switch 58 in the box 56) so that welding current flows when the end of the wire 34 is brought into Contact with the metal work W, and the wire feed motor M automatically is energized, feeding the filler wirev 34 having a diameter of the order of le of an inch fairly rapidly to the welding zone where the metal is melted and fused on the work W under the protection of the gas discharged from the nozzle 52. The gas within the gun also protects the nozzle 56 from the oxygen in the atmosphere and cools l it somewhat, at the same time being preheated before iiowing over the welding zone.

The gun 56 is easy to handle and vertical and overhead welding can be accomplished with almost the same ease as underhand welding. The invention is especially suitable for welding aluminum and its alloys, since aluminum is a good electrical conductor and is flexible in the form of a wire. The transparent cover 53 enables the operator to observe the condition of the wire nozzle 55 during welding, so that the welding current circuit can be opened in case the nozzle 50 appears to be overheated.

In general the rod or wire feed should be fast enough so that melting of the rod or wire away from the welding zone, between the Work and the nozzle, due to the welding current, is prevented. This is important in metals such as aluminum and the alloys thereof. For ller wire of aluminum sizes up to and including ,le inch in diameter, the welding current capacity of the machine is of the order of 300 amperes, and the wire-feed rate is of the order of 300 inches per minute. In welding aluminum without flux, according to the invention, argon gas supplied at the rate of about 35 cubic feet per hour is recommended.

In Fig. 3 there is shown a modified gun 66 comprising a cylindrical handle 68 of insulating material containing a novel head 'I6 comprising a gas distribution and wire contactor block 12 of, electrically conductive metal such as copper which also serves as a holder for the removable wire nozzle lll and as a common terminal for the argon gas line 38, the vvire conduit 36 and a welding current conductor lli). The block i2 is secured in place in the tubular handle by a screw 16. The

hose 42 is attached to the handle 68 by suitable means including a bushing 18. In this modiiication, a manually operated control switch 8% comprising a slide button 82 is mounted on the handle E8. The switch 83 is electrically connected to the control means I4 on the dolly I0 by an insulated cable `83 which also extends through the hose 42.

In Fig. 3, as in Fig. 2, the wire nozzle 'HI is curved so as tolgradually change the direction of the wire 34 as it moves therethrough, and at the same time it helps conduct the welding current to the Wire by brush contact, due to the tendency ofy the wire always to engage the internal walls of the nozzle as the wire is positively pushed therethrough, and continuously bent by the Shape of the nozzle. This assures good electrical contact and helps prevent the wire from welding to the nozzle. The end of the wire nozzle 'I4 is surrounded by a gas nozzle in the form of a coneshaped cup 34- of ceramic material which is removably attached to the tubular handle t8 by a suitable ferrule 86, the cup being held in place in the ferrule by a screw 88.

The block l2 is provided with a cap 90 threaded thereon and to which are attached the conductor 40 (by a screw 92), the wire conduit 3% (by a terminal nipple), and the'argon gas feed line 3B. The nipple is threaded through a hole in the cap 90 and projects into a socket in the block l2, providing a substantially continuous passage for the wire 34. The wire contact nozzle It is removably threaded into a similar socket in the front oi the block. The block 'IB is also provided with a gas distributing system consisting of a gas manifold in the back thereof, and a group of longitudinal gas passages arranged in a concentric circle about the longitudinal axis of the block, each of which passages terminates in a radial outlet 9| which discharges the gas into an annular recess 94 in the front of the block, so that completedistribution of the gas is eiected as the gas flows into a gas expansion chamber 96 around the nozzle I4 in the handle 68. The arrangementI is suchA that a non-turbulent stream of preheated gas is dischargedV from the cup 84 around the heatedV end of the ller metal wire 34 as the wire emerges from the nozzle l, effectively shielding the fusing metalin the welding zone on the work from the atmosphere. The relatively long nozzle I4 very efectively conducts current to the wire 34 as the latter moves therethrough.

In some cases it is necessary to water-cool the nozzle through which the wire is fed. The modication shown in Figs. 4-5 illustrates how this is accomplished according to the present invention. The nozzle QB is tapered externally to provide suiiicient room for a cooling water inlet passage |00-and anoutlet passage H32 which are connected by a cross passage IM near the nose of such nozzle. The ferrule |86 and cup IS are similarly tapered internally, providing a frusto-conical gas passage Hi) therebetween. The cup |08 is removably secured to the ferrule |06 by a ring-nut l I2. The block I |11 is also provided with inclined cooling water inlet and outlet passages H and M 8 which communicate with the passages |68 and |02 in the nozzle, through arcuate grooves |20 and |22, respectively, in the inner face oi the nozzle-permitting the nozzle 98 to be Screwed tightly against the block It without risk of shutting oi the flow oi cooling water.

, Also, in some cases, moisture and/ or air is entrained with the wire 34 as it is fed through the device, which contaminates the weld. This is overcome by the present invention, as shown in Figs. 4.-6, by means of a terminal nipple |24 having radial gas passages |28 in communication with the annular gas manifold |28 between the cap |38 and the block llfi. The passages |26 direct some of the inert gas to flow under pressure in the wire passage, causing some back-pressure of warm inert gas, providing a dam or block which dries the surface of the wire and effectively prevents air and/or moisture from being entrained with the wire 34 into the welding zone. In this case the gas is supplied to the head through tube 33, iiowing from the manifold `|28 through angularly inclined gas passages |32 in the block l I4 to the radial ports |34. Suitable annular sealing gaskets |36 and |38 are provided between mating surfaces of the cap |38 and block ill to prevent any leakage of water or gas.

As shown in Fig. 7, cooling water is supplied to the head through a ilexible conduit i containing a shut-of valve It and a solenoid-valve |45. rillu-e water is conducted irom the head through a flexible conduit Iii? which empties in a sink 49. The motor lvl is regulated by a motor speed governor control ll, such as that of Patent 2,445,72g, for example. The welding current is supplied by a generator or transformer |53 the output of which is conducted to the work W by a ground conductor |55 and to the wire 312 by the busbar conductor Mi.

Referring new to Fig. 8, the generator or transformer |553 is connected tc welding supply lines |51 by a disconnect switch 58 and by a relay or contacter Itl having an input circuit |63, |65. When the input circuit It, H55 is energized and the contactor itl is on, making the conductors i8 and |55V live, this condition is indicated by the illumination oi the signal lamp 52 which is connected across the input circuit it, |55 of the contactor iti by conductors It? and |59, the latter containing a current limiting resistance IiI. rEhe line contains a safety fuse |13 and is connected to one side of a supply circuit il?. rlhe line itv is connected to the other side of circuit Ill through the upper poles I`l8 of switch Eil and a fuse Il.. lThe rod reed motor M comprises a series field winding |18. and an armature till. Une side oi the armature is connected by a wire it to one side of supply circuit il? via the line |53. rEhe other side vof the armature iti is connected tothe other side of supply circuit Il'l via line i8?, containing the double-pole double-throw rod or wirefeed switch 58, contacts |39 of a current relay ISI, and governor control |5I, and line |67. The eld winding I'i is connected by wires |93v to. the stationary poles of such switch 58. The contacts Iil of the relay IQ! are shunted by a condenser |95. The current relay |9| is provided with a portion I8? of the conductor d, so that current flowing in the latter creates a eld which closes normally open contacts |39 of the relay 58|, which contacts otherwise remain open, openingr the supply circuit of the motor M. Thus, when the switch 5t is closed and welding current flows in the conductor fic, the motor M runs at the speed determined by operation of the control ISI.

The'solenoid-valves 39 and |45 which control the now oi gas and water, respectively, have their coils Ziltand 2532 connected in parallel with each other across the lines |63 and |65 by conductors 26d and 2536. Thus, the coils are energized by the supply circuit III, opening the valves 39 and lfiii, when the inching button 68 is unlocked, connecting the upper poles |18 thereof'. The

, 7 motor speed governor control l! is connected to lines l0 and |55 by conductors 208 and 210 when it is desired to control the speed of the Vmotor M in accordance with the welding voltage.

Otherwise the control may operate to keep the speed of the motor constant.

The control |51 is preferably of the electronic type disclosed and claimed in Patent 2,445,789, which is mechanically and/or electrically associated with the motor M, and operates automatically when the motor M is rotating to maintain the speed of the motor at a very constant predetermined value, if desired, so that the rod or wire 34 is fed thereby at a critical rate, which has been found to be very important in welding hot-short metals such as aluminum according to the invention. In the case of stainless steel, however, the control is preferably responsive to the value of the welding current voltage, so that such voltage is kept constant by the control.

In operation, the rod feed switch 58 is closed in feed position and the rod 34 is fed or inched by pushing down and closing the lower poles 2|2 of the switch 60. This closes a line 2M in shunt with contacts l89 of the current relay |91, energizing the motor M. When the Wire or rod 34 is in the desired position, the switch 60 is released, connecting the upper poles |13, and the work W is touched with the end of the rod 34. This causes welding current to ow and the motor M to feed the rod Sfat a rate determined by the control |51, which continues until the welding action is interrupted by quickly pulling the rod out of the welding zone. This opens the welding current circuit, 'the current relay contacts |89 open, and the rod feed motor M stops.

The invention is quite suitable for overhead and vertical as well as horizontal welding, since it is only necessary for the operator, after making the apparatus ready, to point the wire or rod in the desired direction and then touch the work therewith. Thereupon, the rod or wire is fed automatically toward the work as the operator holds the gun stationary or moves it along a desired path at any rate he may choose, depending upon the desired vthickness of the weld. The resulting welds are sound and relatively free of undesirable foreign matter, due to the operation of the air and/or moisture block or trap of inert gas in the gun.

I claim:

1. In a continuous-feed metal-arc Welding gun,

the combination with a tubular handle of in-` sulating material, a gas cup removably mounted on the outer end of said handle, a block of metal removably secured within said handle and having a central passage for wire filler metal, and also having separate gas and water passages, a nozzle of metal removably mounted on the front of said block and being spaced from the inner surface of the handle and cup to provide an annular gas passage, said nozzle having a, wire passage in line with the corresponding wire passage in the block, said nozzle also having a cross Water passage in communication with inlet and outlet Water passages communicating in turn with the corresponding water passages in the block, a metal cap mounted on the back of said block, a flexible wire conduit having a terminal nipple mounted in a hole in said cap and extending into a socket in said block concentric with said wire passage, said cap and .block having means providing an annular inert gas distributing manifold in communication with said gas passages in the block, and separate arcuate water transfer spaces in communication with said inlet and outlet water passages in the block, inlet and outlet water pipes connected to said cap, and a welding current supply line also connected to said cap.

2. In a continuous-feed metal-arc welding gun, the combination as defined by claim 1, in which the terminal nipple is provided With lateral gas passages in communication with said inert gas manifold, whereby inert gas flows into the llerwire passage under pressure and minimizes the ilow of atmospheric air and moisture with the ller wire into the nozzle.

3. In a gas shielded metal-arc Welding gun, a tubular handle of insulation material containing a combined gas distributing and electrical contact block of metal secured therein, said block having an axial passage for guiding wire, a nozzle of metal removably secured to the iront of said block and having a wire passage in line with the corresponding passage in the block, a cap of metal mounted on the back of said block, a wire supply conduit having a terminal nipple extending through and iitting an axial hole provided therefor in the cap and fitting in a socket in the back of the block, the end wall of the cap being spaced from the end of the block and providing a gas manifold, a gas supply pipe connected to said cap for delivering gas under pressure to said manifold, a welding current supply line having one end connected to said cap, said block having a plurality of gas passages in communication with said gas manifold for conducting the gas to a space in the tubular handle in front of the block around the nozzle, and a gas discharge cup removably connected to the front end of said handle in spaced relation to said nozzle.

4. In an inert-gas shielded continuous-feed metal-arc welding gun, the combination with an inner nozzle having a passage through Which filler metal wire is fed and welding current is conducted to such wire, and outer nozzle means including a gas cup for flowing inert gas in an annular stream over said nozzle and the wire and the welding zone as the wire emerges from the nozzle, of common head means for conducting welding current to said nozzle and also conducting inert gas to said outer nozzle means, said common means comprising a metal block to which said inner nozzle is removably attached, said block having a wire passage in line with the corresponding passage in the inner nozzle, and said block also having longitudinal inert-gas supply passages leading to an annular space between said inner nozzle and said outer nozzle means; said head means being also provided with inertgas supply passages leading to the wire passage, so that air and moisture entrained with the wire is prevented from entering the welding zone, by back-pressure of the inert gas.

ALBERT W. BAIRD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED 'STATES PA'IE-NTS Number Name Date 1,644,237 Christensen Oct. 4, 1927 1,746,207 Alexander Feb. 4, 1930 1,953,915 Burgett Apr. 3, 1934 2,376,265 Meredith May 15, 1945 2,468,804 Breymeier May 3, 1949 

